Retrievable casing tester



Oct. 29, 1963 e. E. LAYTON RETRIEVABLE CASING TESTER 2 Sheets-Sheet 1Filed Jan. 25, 1960 INVENTOR. GERALD E. LAYTO/V ATTORNEY Oct. 29, 19635, LAYTON 3,108,467

RETRIEVABLE' CASING TESTER Filed Jan. 25, 1960 2 Sheets-Sheet 2 9 29 3B25 24 I 26 2s I l3 3 so l4 l6 I? 3 F /'g. 5

[ Fig. 6

INVENTOR. GERALD E. LAYTO/V I Fig. 4

ATTORNEY United States Patent Ofi ice hill-8A6? Patented Oct. 29, 19633,108,467 RETRIEVABLE CASING TESTER Gerald E. Layton, 3668 MonacoParkway, Denver, Colo.

Filed Jan. 25, 1960, Ser. No. 4,448 4 Claims. (43]. 73-405) Infunctional analogy with, as a development from, and an improvement incertain respects over the disclosures of my application for LettersPatent of the United States filed on June 15, 1959, Serial No. 820,206,this invention relates to equipment useful in the conditioning of deepearth bores, such as oil wells, and the like, for extension andproduction, and more particularly to an equipment unit repetitiouslyapplicable to facilitate test for imporosity of easing lengths asappropriate during placement of the easing for conventional operationwithin a bore, and has as an object to provide a novel and improved suchunit selectively applicable to and retrievable from sealing coactionwith the lower end interior of a casing length entered to ultimate useposition at any depth within an earth bore.

A further object of the invention is to provide a novel and improvedunit selectively applicable to and retrievable from sealing coactionwith the lower end interior of a casing length Within an earth bore inreaction to \means and influences conventionally complementary to placement of the casing.

A further object of the invention is to provide a novel and improvedrepetitiously-employable, retrievable unit selectively applicable tosealing coaction with the lower end interior of a casing length withinan earth bore in reaction to fluid pressures regulably applied to thecasing interior thereabove.

A further object of the invention is to provide a novel and improvedrepetitiously-employable unit selectively applicable to sealing coactionwith the lower end interior of a casing length within an earth bore inreaction to fluid pressures regulably applied to the casing interior andretrievable upon abatement of such pressure through the sole agency of aline conventionally complementary to casing placement operations.

A further object of the invention is to provide a novel and improvedcasing testing adjunct selectively applicable to and retrievable fromsealing coaction with the lower end interior of a casing length withinan earth bore that is immediately recoverable after each instance ofpractical use in condition for reuse to leave unaltered the casing zonethereby engaged.

A further object of the invention is to provide a novel and improvedcasing testing adjunct selectively applicable to and retrievable fromsealing coaction with the lower end interior of a casing length withinan earth bore that is compact in a light-weight unitary assemblyamenable to controlled adjustment longitudinally of and operativelywithin earth bore casings in attachment to a line conventionallycomplementary to casing placement operations.

A further object of the invention is to provide a novel and improvedcasing testing adjunct selectively applicable to and retrievable fromsealing coaction with the lower end interior of a casing length withinan earth bore that is expedient of adaptation at the side of use foroperative coaction with casings and casing components of diverse sizeparticularity. I

A further object of the invention is to provide a novel and improvedcasing testing adjunct selectively applicable to and retrievable fromsealing coaction with the lower end interior of a casing length withinan earth 'bore that is expedient of adaptation at the site of use foroperative coaction with casings and casing components in diverseadjustments to differing field conditions.

A further object of the invention is to provide a novel and improvedconstruction and operative correlation of elements constituting atesting adjunct selectively applicable to and retrievable from sealingcoaction with the lower end interior of a casing length within an earthbore.

A further object of the invention is to provide a novel and improvedretrievable casing tester that is simple and inexpensive of productionfrom available materials in an extensive range of desired sizes, that isdurable throughout a long life of repetitious use, that is effectivelyoperable in automatic reaction to influences regulably applied to andthrough the end of the casing accessible at ground level, and that ispositive and efficient in attainment of the ends for which designed.

With the foregoing and other objects in View, my invention consists inthe construction, arrangement, and operative combination of elements ashereinafter set forth, pointed out in my claims, and illustrated by theaccompanying drawings, in which- FIGURE 1 is a vertical sectionlongitudinally through the lower end portion of a casing lengthpositioned for placement Within an earth bore with a typical embodimentof the invention shown in side elevation as associated with the casingfor sealing coaction therewith, an intermediate length portion of theview not essential to an understanding of the invention being brokenaway to conserve space.

FIGURE 2 is a longitudinal section, on a relativelyenlarged scale,axially through the lower portion of the embodiment according to and aspositioned in the showing of FIGURE 1.

FIGURE 3 is a longitudinal section, on the same scale as FIGURE 2,axially through the upper portion of the embodiment according to and aspositioned in the showing of FIGURE 1, an intermediate length portion ofthe continuous member comprised in the view being broken away toconserve space.

FIGURE 4 is a longitudinal section similar to FIGURE 2. showingtelescopically-associated elements thereof in an alternative conditionof operative interrelation thereby assumed during transit of theassembly to and from sealing coaction with conventional casingcomponents.

FIGURE 5 is a fragmentary side elevation, partially in section, of thelower end of the organization according to FIGURES l, 2 and 4 assize-adapted within the contemplation of the invention.

FIGURE 6 is a fragmentary side elevation, partially in section, of thelower portion of the organization according to FIGURES 1, 2 and 4 asalternatively coupled within the contemplation of the invention.

Deep earth bores developed for the production of water, petroleum oils,gases, and the like, are commonly conditioned for production, and forextension in depth, through the provision of bore linings in the form ofcontinuous lengths of rigid, tubular, usually-metallic casing assembledthrough the intercoupling of separate, like sections at the mouth of thebore as the completed length is lowered therethrou gh. As conditionedfor casing, the bore confines, or may be charged with, a column ofliquid which is availed of to in an important measure counteract theprogressively-increasing weight of the casing length descending therein,for which purpose the otherwise open, lower end of the casing length isobstructed by a tubular plug, termed a float collar, coaxially andfixedly associated in diverse conventional structural particularity withthe end of the casing first inserted in the bore to restrict, but not toclose, the path of liquid access to the casing interior, which plug, orfloat collar, is subsequently drilled out of the casing upon completionof the desired casing placement. It being customary to finally cementthe placed casing in its use posit-ion within the bore, and it beingmaterial to ultimate efiicient production through the casing that thelatter be free from leakage of confined flow therethrough, it isapproved practice to pressure-test the casing length [for imporosityafter placement and before cementing thereof relative to the bore, inexpeditious, economical, and practical furtherance whereof the instantinvention is directed to the provision of an adjunctive unit retrievablycoactab'le with the float collar of a placed casing length to functionas an abutment closing the lower end of the length in reaction topressures applied interiorly \of the casing therea-bove for test ofcasing integrity.

'Iypifying the use environment of the invention, the lower end portionof a continuous length of conventional tubular Casing is indicated bythe numeral and shown in FIGURE 1 of the drawings as loosely engaged atany appropriate depth within an earth bore for fixed emplacementrelative thereto, and as furnished with a conventional, tubular,cementitious float collar 11, carried as is customary in a coupling 12threadedly connectible with and as an extension of said casing length,partially obstructing its otherwise fully open lower end to represent aflat, annular shoulder transversely of and opposed to the interior ofsaid length 10.

Selectively and retrievably operable to realization of its purposeswithin the environment typified by the casing portion 10, float collar11, and coupling 12, the improvement of the invention is anaxially-elongated, unitary assembly of the coaxial,relatively-reciprocable cylindrical elements hereinafter specifiedhaving a maximum diameter less than the interior diameter of the casing10 adapting it for free reciprocation within the casing.

In accordance with and to give effect to the principles of theinvention, the lower end of the retrievable unit assembly is constitutedas a rigid, tubular member l3 freely and loosely reciprocable interiorlyof the casing 10 in a length desirably several times its exteriordiameter and a tubular nose plug 14 detachably coaxial in threadedengagement with the lower end of said member. In a maximum diameterexceeding that of the open throat through the float collar 11 wherewithit is designed to coact, the nose plug 14 surrounds an axial boreslightly smaller than that of the member 13, is exteriorly reduced andexternally threaded at one end to the form of a shouldered stemengageable in and with the internal threads of the lower end of saidmember, mounts a sealing ring 15 at the junction of its threaded stemwith the plug body position to compress against the adjacent end of themember 13 and close the thread joint when the plug is fully seated inthe member thereby, is exteriorly reduced and tapered at its other endto the form of a shouldered nose extremity 16 sized to enter andsubstantially fill the open throat through the float collar 11 of anassociated casing, and is circumferentially rabbeted at the junction ofsaid extremity 15 with the plug body for retentive accommodation of asealing ring 17 thereby disposed to close and compress against theopposed peripheral corner of the float collar throat receptive of theplug extremity 16. At its end remote from the plug 14 the member 13 isinteriorly shouldered about a slightly-reduced bore wherein a tubularsleeve 18 is slidably and coaxially accommodated telescopic,reciprocable association with said member through a range limited in onedirection by an annular shoulder exteriorly about the end of said sleeveopposed to the plug 14 adapted for engagement against the interiorshoulder of the member 13 for determination of maximum sleeve extensionfrom the member, and limited in the other direction by a washer 19 aboutand inwardly adjacent the sleeve end exterior to the member detachablyretained thereon between a snap ring 20 groove-seated in the sleeve atthe side of the was-her remote from the member 13 and a sealing ring 21at the side of said washer opposed to said member in position to attimes close the slide joint between said sleeve and theinteriorly-shouldered endof the member. The tubular wall of the sleeve18 is intersected by angularly-spaced slots 22 longitudinally thereof ina length-correlation therewith such as to fully expose the slots whenthe sleeve is at the limit of its extension outwardly from the member13, as in FIGURE 4, and to wholly confine said slots within said memberwhen the sleeve is at the limit of its retraction inwardly thereof, asin FIGURE 2.

Telescopically, coaxially, and reciprocably associated with the sleeve'18 in the same manner as the latter is associated with the member '13,a rigid tube 23 slidably accommodated through a slightly-reduced bore atthe interiorlyshouldered end of said sleeve exterior to said member isformed with an annular shoulder exteriorly of its end directed towardthe plug 14 adapted to at times engage the interior shoulder of thesleeve as a stop limiting extension of said tube from the sleeve in adirection away from said plug and is provided with a washer 24, snapring 25, and sealing ring 26, functionally and structurally identical,save as to size, with the washer and ring assembly 1920-21 of the sleeve18, operable at times to limit retraction of the tube 23 within thesleeve and concomitantly close the slide joint there-between. The tube23 is formed with singularly-spaced, longitudinal slots 27 in a lengthcorrelation such as to fully expose the same when the tube is at thelimit of its extension outwardly from the sleeve 18, as in FIGURE 4, andto wholly confine said slots within said sleeve when the tube is at thelimit of its retraction inwardly of the sleeve, as in FIGURE 2. The tube23 is formed with a shouldered, annular, interior restriction 28 adaptedto function as a valve seat at the zone thereof embraced by the washer24 and with holes 259 in an angular spacing radially through its walloutwardly adjacent said restriction in a direction away from the sleeve18, beyond which holes said tube continues in substantial elongation toan externally-threaded, free end termination.

In a preferred organization appropriate for intended coaction with deepbore casings, the outward termination of the tube 23 threadedly engageswithin an end of a coaxial tubular coupling 30 thereto secured by aclamp nut 31 and a link 32 slidably coaxial with said coupling by virtueof a lost-motion connection thereto, such as a pin 33 fixeddiametrically of the coupling end remote from the tube 23 through and towork in a diametric slot 34 longitudinally of the link, coaxially anddetachably mounts for actuation therewith a cylindrical stem 35extending from the end thereof adjacent the tube 23 and adapted fortelescopic reception and reciprocation within the latter. For purposesof expedient separable, operative interassociation, the end of the link32 mounting the stem 35 may be formed with a diametric andaxially-opening keyway slot adapted to laterally receive and looselyaccommodate a necked, terminal head 36 on the coacting end of the stem,and the end of said stem 35 remote from the link 32 is shouldered abouta coaxial terminal finger 37 sized to freely enter the restriction 23 ofthe tube 23 through a sealing ring 38 compressible at times between theopposed shoulders of said stem and restriction. The lost-motion travelof the link 32 relative to the coupling 30 and the length of the stem 35extension axially from said link are proportioned to enter the stemfinger 37 fully within the restriction 28 of the tube 23 and tocompressive engagement of its adjacent shoulder with the sealing ring 38when the link 32 is at the limit of its travel inwardly of the coupling30, as in FIGURE 2, and to retract said stem and its finger 37 away fromsaid restriction and into clearing relation with the holes 29 of thetube 23 when said link is at the limit of its travel outwardly withrespect to the coupling, as in FIGURE 4.

The end of the link 32 remote from the coupling 30 is externallythreaded for connection to and within one end of an elongated,relatively-massive bar 39 adapted to function, when appropriate, as ajar in a well-known manner accommodated by the lost-motion connection ofthe link to the coupling 30, which bar is expediently provided withchordal flats 40 to facilitate its threaded interassenrbly with otherelements of the organization and is secured in operative associationwith the link by a clamp nut 41. The end of the bar 39 remote from thelink 32 is formed as an externally-threaded, coaxial stud 42 engageablewithin and to mount a coaxial thimble 43 attached at, or through, itsclosed end to a flexible manipulating line 44 customarily available atthe site of bore casing operations to effect transit of equipment andfacilities interiorly of the bore; said thimble desirably presentingexterior, angularly-related surfaces for engagement by a tool applicableto effect relative rotation of the thimble with respect to the stud 42and bar 39'. To guide and operatively center the bar 39 interiorly ofthe casing 10, it is practical to provide on and exteriorly about andnear the upper end of said bar a radially-resilient basket yieldablyadaptable to sliding coaction with casing of diifering sizes, and such abasket is typified as consisting of like collars 45 slidably androtatably embracing the bar 39 in a variable spacing axially of the bardetermined by a plurality of angularly-spaced, convexly-bowed springstrips 46 fixedly connecting therebetween, which basket is retained inself-adjusting relation with the bar between snap rings 47 groove-seatedcircumferentially of the bar in a spacing axially thereof exceeding thelength of the unstressed basket.

Practical use and operation of the organization illustrated and thus fardescribed should be reasonably apparent from the foregoing explanationof structure. In an integrated assembly of suitable size provided with anose extremity 16 engageable through the open throat of the float collar11 known to be associated with the casing 10, the improvement of theinvention is lowered through the casing in suspension from the line 44with the telescopically-associated elements thereof at thegravity-induced limit of their relative extension in the relationshiprepresented by FIGURE 4. Extended as shown in said latter view duringthe lowering operation, a passage for uprise of casing fluid charge isopen through the bore of the plug 14, the interior of the member 13, thebore of the sleeve 18 and radially therefrom through the slots 22, thebore of the tube 23 and radially therefrom through the slots 27, thethroat of the restriction 28 and radially of the tube 23 thereabovethrough the holes 29, whereby unimpeded descent of the assembly throughthe casing is assured; any lodgemcnt of the assembly during descentthrough the casing being readily relieved by linear agitations of theline to consequent actuation of the jar typified by the bar 39 and itslost-motion connection. Approach of the plug 14 to the float collar 11effects engagement of the nose extremity 16 within the throat of thefloat collar and seating of the ring 17 in sealing coaction with theupper rim of the throat, whereafter, under the influence of theirinherent weights and consequent loadings, the telescopically-associatedelements of the assembly continue to descend to the limit of theirrelative retraction and assume the positions represented by FIG- URE 2wherein fluid passage from beneath the float collar and through theassembly to the interior of the casing is interrupted and passage offluid in the opposite direction from the casing interior and to the zonebeneath the float collar is inhibited by the seals closing all of theslide joints of the unit. With the assembly seated on the float collar,compacted, and sealed as shown and described, fluid is introduced underpressure to the interior of the casing thereabove to a degree and for atime appropriate to determine imporosity of the casing as reflected byvariations of sustained pressure, the reaction of the fluid sointroduced under pressure on the unit resisting its escape through thefloat collar being but to augment the sealed coaction of the unitelements. Upon release of the pressure interiorly of the casing, tensionapplied to the line 44, supplemented it needful by jar effect developedthrough the bar 39, first acts to extend the telescopically-associatedelements of the unit for consequent opening of a flow passagetherethrough as above set forth and then serves to lift the unit lfIOIIlthe casing with negligible resistance by the casing liquid charge toultimate recovery of the unit in condition for immediate reuse.

The detachable interassociation of the plug 14 and member 13 qualifies agiven structural embodiment of the invention for adaptation to use inand with casings of diverse diametric sizes accommodative of unittransit therein and for operative coaction with float collars ofdifferent throat sizes through simple selection and attachment to themember of a plug of appropriate diameter and nose extremity size. It iseminently practical to provide a plurality of plugs 14 respectivelyformed with a nose extremity 16 sized in shouldered relation with theplug body to enter and fill a float collar throat of known conventionalparticularity, so that, as typified by FIGURE 5, a plug 14 proportionedas represented in FIGURES 1, 2 and 4 expediently may be replaced by afunctionallyidentical substitute plug 14' having an externally-threadedstem connectible to the lower end of the member 13 and provided with thesealing ring 15 which distinguishes from the plug 14 only in anoperatively-correlated variation of body 14', nose extremity 16', andsealing ring 17 diameters. With a plug 14' terminating the unit in adiametric size exceeding that of the associated member 13 it isdesirable that the end of said member remote from the plug be radiallyenlarged for unit-guiding coaction with the casing interior, for whichpurpose an annular collar 48 adapted to slidably embrace said member maybe engaged therewith and retained adjacent the member end remote fromthe plug between snap rings 49 received in spaced grooves '50circumierentially of the member exterior.

Further adaptation of the unit to effectuate desired operations incertain of varying situations and under difiering field conditions isaccommodated by forming the externally-threaded end portions of the tube23, link 32, and bar 39, and the thread components coactable therewith,to like diametric size and thread pitch, whereby to provide that thethimble 43 may be directly connected, at option, to either the link 32or tube 23 with consequent elimination of the elements and featureshereinabove described as normally therebetween. As is fully obvious,connection of the thimble 43 directly to the outward, threaded end ofthe link 32 reduces the length and weight of the unit assembly throughelimination of the bar 39 with retention of all fiunctional propertiesand relationships of the improvement, including the lostm-otion linkageoperable under reduced mass with jarring effect, as previouslydiscussed. Alternative connection of the thimble 43 directly to theoutward, threaded end of the tube 23, exemplified by FIGURE 6, yetfurther reduces the length and weight -of the resulting assembly throughelimination, in addition to the bar 39, of the coupling 30, link 32, andstem 35, with consequent removal of the lost-motion linkage and thefunctions peculiar thereto, it being requisite to practical use of theassembly as so modified that, in the absence of the stem 35 and itsfinger 37 sealably coactable with the restriction 28, the holes 29 ofthe tube 23 be plugged, or otherwise closed, as indicated, to fully stopany passage for fluid flow through the unit in its retracted state,other than which the operation and functional applicability of thearrangement according to FIGURE 6 are the same as those of theembodiment first described.

Since changes, variations, and modifications in the form, construction,and arrangement of the elements shown and described may be had withoutdeparting from the spirit of my invention, I wish to be understood asbeing limited solely by the scope of the appended claims, rather than byany details of the illustrative showing and foregoing description.

I claim as my invention:

1. A retrievable casing closing means adapted to freely descend througha tubular casing having fluid therein, for cooperation with a floatcollar disposed within said casing at the location where said casing isto be closed 7 and extending inwardly from the casing Walls, saidclosing means comprising:

(a) a telescopically associated extensible and retract able assembly ofat least two cylindrical elements loosely receivable within the casingfor free reciprocation longitudinally thereof;

(b) each of said elements having a bore extending longitudinallytherethrough, the bores in said elements being coaxial and extendingbetween an open end and an opposite closed end of said assembly;

() means at the closed end of said assembly connectable with a linemanipulatable to regulate assembly travel relative to the casing;

(d) means at the open end of the assembly adapted for sealing coactionwith the float collar at the limit of assembly travel downwardly throughthe casing, said means having a bore extending therethrough coaxial withthe first mentioned bores;

(e) at least one of said cylindrical elements having a plurality ofradially extending openings therein communicating said bores throughsaid one cylindrical element directly with the exterior of said assemblywhen extended whereby said assembly can freely descend, as extended,through the casing with the fluid therein passing substantially freelythrough said bores and said openings;

(7) said one element being reciprocally receivable within the bore ofanother in retracted position of said assembly;

(g) said one element having spaced shoulder and abutment means thereonto alternatively limit extension and retraction of said one element withrespect to said another element, said shoulder means engaging saidanother element interiorly thereof, and said abutment means engagingsaid another element exteriorly thereof;

(It) said abutment means comprising a laterally projecting member and acompressible sealing means for fluid sealing said elements with oneanother in retracted position of said assembly, said sealing means beingdisposed in underlying abutting relation to said member for engagementexteriorly with said another element;

(i) said openings extending over a substantial longtudinal portion ofsaid one element but terminating within the area of said one elementreciprocally receivable within said another element in retractedposition of said assembly, whereby as retracted, said assembly will notpass fluid therethrough;

( said member providing a surface against which fluid under pressure canact to press said assembly, as retracted, into sealing engagement withthe float collar, and to press said sealing means against said anotherelement.

2. A retrievable casing closing means as defined in claim 1 and furtherincluding a third cylindrical element,

said third cylindrical element being loosely receivable within saidcasing for free reciprocation longitudinally thereof, said third elementhaivng a bore extending longitudinally therein coaxial with the firstmentioned bores, a stem reciprocally slidable in the bore of said thirdelement, said third element having a restriction therein cooperable withsaid stem to close said bore in said third element, said third elementhaving radial openings therein above said restriction and past whichsaid stem is slidable, connecting means coupling said stem to said meansmanipulatable to regulate assembly travel for control thereby, saidthird element being reciprocally receivable within the bore of said oneelement in retracted position of said assembly; said third elementhaving spaced shoulder and abutment means thereon, to alternativelylimit extension and retraction of said third element with respect tosaid one element; said shoulder means on said third element engagingsaid one element interiorly thereof, and said abutment means on saidthird element engaging said one element exteriorly thereof, saidabutment means on said third element comprising a laterally projectingmember and compressible sealing means for fluid sealing said thirdelement with said one element in retracted position of said assembly,said last mentioned sealing means being disposed in underlying abuttingrelation to said last mentioned member for engagement exteriorly withsaid one element; said last mentioned member providing a surface againstwhich fluid under pressure can act to press said last mentioned sealingmeans against said one element.

3. A retrievable easing closing means as defined in claim 2 wherein saidconnecting means comprises a socket connected to said stem and alost-motion connection between said socket and said means manipulatableto regulate assembly travel.

4. A retrievable casing closing means as defined in claim 1 wherein saidmeans adapted for sealing coaction with the collar is a cylindrical plughaving a diameter exceeding the interior diameter of the float collar,said plug being detachably connected to said assembly as a lowerextension therefrom, said plug being formed with a bore diametricallysmaller than the interior diameter of the float collar, said plug havinga frusto-conical nose adapted to fully enter the float collar, said plughaving a shoulder projecting about and above said nose, said plugcarrying sealing means underlying said last-mentioned shoulder forsealing engagement with the throat collar.

References Cited in the file of this patent UNITED STATES PATENTS2,128,716 Smith Aug. 30, 1938 2,129,216 Johnson Sept. 6, 1938 2,287,319Miller June 23, 1942 2,868,297 Lamberson Jan. 13, 1959

1. A RETRIEVABLE CASING CLOSING MEANS ADAPTED TO FREELY DESCEND THROUGHA TUBULAR CASING HAVING FLUID THEREIN, FOR COOPERATION WITH A FLOATCOLLAR DISPOSED WITHIN SAID CASING AT THE LOCATION WHERE SAID CASING ISTO BE CLOSED AND EXTENDING INWARDLY FROM THE CASING WALLS, SAID CLOSINGMEANS COMPRISING: (A) A TELESCOPICALLY ASSOCIATED EXTENSIBLE ANDRETRACTABLE ASSEMBLY OF AT LEAST TWO CYLINDRICAL ELEMENTS LOOSELYRECEIVABLE WITHIN THE CASING FOR FREE RECIPROCATION LONGITUDINALLYTHEREOF; (B) EACH OF SAID ELEMENTS HAVING A BORE EXTENDINGLONGITUDINALLY THERETHROUGH, THE BORES IN SAID ELEMENTS BEING COAXIALAND EXTENDING BETWEEN AN OPEN END AND AN OPPOSITE CLOSED END OF SAIDASSEMBLY; (C) MEANS AT THE CLOSED END OF SAID ASSEMBLY CONNECTABLE WITHA LINE MANIPULATABLE TO REGULATE ASSEMBLY TRAVEL RELATIVE TO THE CASING;(D) MEANS AT THE OPEN END OF THE ASSEMBLY ADAPTED FOR SEALING COACTIONWITH THE FLOAT COLLAR AT THE LIMIT OF ASSEMBLY TRAVEL DOWNWARDLY THROUGHTHE CASING, SAID MEAN HAVING A BORE EXTENDING THERETHROUGH COAXIAL WITHTHE FIRST MENTIONED BORES;